The present invention pertains to a switching bridge for an electrical switch, particularly for a safety switch.
A switch bridge arrangement of the type under discussion normally includes a number of contact bridges superposed on each other or positioned one after another and arranged movably in the windows or openings of the switch bridge housing. The contact bridges which support at their ends contact pieces are normally positioned under the pressure of respective pressure or contact springs.
Switch bridge arrangements of the foregoing type are known. All contact springs in such switch bridge arrangements are formed as helical springs which are inserted in respective windows of the switch housings so that one end of each spring is supported against the lower wall of the window whereas the other end of the spring is supported against the respective contact bridge. The disadvantage of such arrangements resides in that only a manual assembling of such an arrangement is possible due to the fact that each contact bridge can be inserted into the window and properly placed with respect to the helical spring by hand. A further disadvantage of conventional arrangements is that the helical spring presses against the contact bridge only in the middle thereof and no support of the contact bridge can be effected. Thus each contact bridge is provided in the longitudinal direction with two-side projections or similar guide pieces which would engage at the edges of the window and thereby hold the contact bridges against displacement in the longitudinal direction. In case of a great number of switching movements, which each contact bridge performs in the window, an extremely great rubbing action between the switch housing and the contact bridge, both made in the region of the window of synthetic plastic material, will result. This rubbing occurs at least partially on the contact pieces which become contaminated. Thus the contact safety is negatively affected after some time of use of the switch.